Composition for polishing pad and polishing pad using the same

ABSTRACT

An object of the invention is to provide a polishing pad having the excellent slurry retaining properties and the large removal rate and a composition for a polishing pad which can form such the polishing pad. A composition for polishing pad of the invention is comprising a water-insoluble matrix material containing a crosslinked polymer and a water-soluble particle dispersed in the water-insoluble matrix material. The elongation remaining after breaking is 100% or less when a test piece comprising the water-insoluble matrix material is broken at 80° C. according to JIS K 6251. A polishing pad of the invention is that at least a part of the polishing pad comprises the composition for polishing pad.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a composition for a polishing pad and apolishing pad using the same, and this polishing pad can be suitablyutilized for polishing the surface of semiconductor wafer and the like.

2. Description of the Related Art

As a method for polishing which can form the surface having the highflatness, an attention has been recently paid to CMP (ChemicalMechanical Polishing). In CMP, polishing is performed by flowing down aslurry which is an aqueous dispersion in which abrasives are dispersedto the surface of a polishing pad from an upper side while sliding apolishing pad and a side to be polished.

A factor which has a great influence on the productivity in this CMP isthe removal rate and, this removal rate is expected to be improvedremarkably by setting at a greater amount of the retained slurry thanpreviously used amount.

Hitherto, in CMP, a polyurethane foam containing fine air bubbles hasbeen used as a polishing pad, and polishing has been performed byretaining a pore opened on the surface of this resin (hereinafter,referred to as “pore”).

However, in the polyurethane foam, it is difficult to control thefoaming freely, and it is extremely difficult to control a size offoamed air bubbles, a foam density, and the like through the foamuniformly. As a result, the quality of a polishing pad comprising apolyurethane foam varies, leading to the cause for the varied removalrate and the procession state.

As a polishing pad in which controlling of a pore is easier upon thisfoaming, there are known soluble materials dispersed in a number ofresins described in Japanese Patent laid-open publication Hei 8-500622,Japanese Patent laid-open publication 2000-34416 and Japanese Patentlaid-open Publication 2000-33552, and the like. Among them, theeffectiveness of a polishing pad containing solubles materials issuggested in Japanese Patent laid-open publication Hei 8-500622 andJapanese Patent laid-open publication 2000-33552. However, a matrixmaterial is not studied when it is actually used as a polishing pad.

In addition, a component material is studied in Japanese Patentlaid-open publication 2000-34416 and the more stable polishing and animprovement in the removal rate are recognized but a further improvementin the slurry retaining properties and the polishing rate is required.

SUMMARY OF THE INVENTION

The present invention was done in view of the aforementionedcircumstances, and an object of the present invention is to provide apolishing pad which has the great removal rate due to the excellentslurry retaining properties, and can effectively prevent a decrease inthe retaining properties and the removal rate during polishing and evenafter dressing, and a composition for a polishing pad which can formsuch the polishing pad.

The present inventors studies in detail the mechanism by which theslurry retaining properties and the removal rate are gradually decreasedduring polishing, and the mechanism in dressing in which a pore isformed (face forming) or updated (face updating) on the surface of apolishing pad with a diamond whetstone and the like. As a result, wefound that, when shear stress is exerted on the previous polishing padsurface by the polishing, dressing and the like, an elongation producedon the surface of a matrix material which is a main component materialand, thereafter, the surface is deformed plastically and, thus, a poreis choked. Further, we found that since dusts of not only surface of awafer but also a matrix material itself are produced, these dusts alsochoke a pore. That is, we found that a sufficient improvement in theremoval rate can not be effected for these causes and, as a method forpreventing them, the use of a material having the cross-linkingstructure manifesting the elastic recovery in a matrix material iseffective, which resulted in completion of the present invention.

The present invention is based on the findings described above and canbe described as follows.

1. A composition for a polishing pad which comprises a water-insolublematrix material containing a crosslinked polymer and a water-solubleparticle dispersed in the water-insoluble matrix material.

2. The composition for a polishing pad according to 1 above, wherein theelongation remaining after breaking is 100% or less when a test piececomprising the water-insoluble matrix material is broken at 80° C.

3. The composition for a polishing pad according to 2 above, whereinsaid water-insoluble matrix material is modified with at least oneselected from the group consisting of an acid anhydride group, acarboxyl group, a hydroxyl group, an epoxy group and an amino group.

4. The composition for a polishing pad according to 3 above, whereinsaid water-soluble particle is an organic water-soluble particlecomprising at least one selected from the group consisting of dextrin,cyclodextrin, mannit, lactose, hydroxypropylcellulose, methylcellulose,starch, protein, polyvinyl alcohol, polyvinyl pyrrolidone, polyacrylicacid, polyethylene oxide, water-soluble photosensitive resin, sulfonatedpolyisoprene and sulfonated polyisoprene copolymer, and/or an inorganicwater-soluble particle comprising at least one selected from the groupconsisting of potassium acetate, potassium nitrate, potassium carbonate,potassium bicarbonate, potassium chloride, potassium bromide, potassiumphosphate and magnesium nitrate.

5. The composition for a polishing pad according to 4 above, wherein theamount of said water-soluble particles is 10 to 90% by volume based on100% by volume as the total amount of said water-insoluble matrixmaterial and said water-soluble particles.

6. The composition for a polishing pad according to 1 above, wherein atleast a part of said crosslinked polymer is a crosslinked rubber.

7. The composition for a polishing pad according to 6 above, wherein atleast a part of said crosslinked rubber is crosslinked1,2-polybutadiene.

8. The composition for a polishing pad according to 7 above, whereinsaid water-insoluble matrix material is modified with at least oneselected from the group consisting of an acid anhydride group, acarboxyl group, a hydroxyl group, an epoxy group and an amino group.

9. The composition for a polishing pad according to 8 above, whereinsaid water-soluble particle is an organic water-soluble particlecomprising at least one selected from the group consisting of dextrin,cyclodextrin, mannit, lactose, hydroxypropylcellulose, methylcellulose,starch, protein, polyvinyl alcohol, polyvinyl pyrrolidone, polyacrylicacid, polyethylene oxide, water-soluble photosensitive resin, sulfonatedpolyisoprene and sulfonated polyisoprene copolymer, and/or an inorganicwater-soluble particle comprising of at least one selected from thegroup consisting of potassium acetate, potassium nitrate, potassiumcarbonate, potassium bicarbonate, potassium chloride, potassium bromide,potassium phosphate and magnesium nitrate.

10. The composition for a polishing pad according to 9 above, whereinthe amount of said water-soluble particles is 10 to 90% by volume basedon 100% by volume as the total amount of said water-insoluble matrixmaterial and said water-soluble particles.

11. The composition for a polishing pad according to 1 above, whereinsaid water-soluble particle is provided with an outer shell forinhibiting moisture absorption in at least a part of the outermost part.

12. The composition for a polishing pad according to 11 above, whereinsaid water-soluble particle is an organic water-soluble particlecomprising of at least one selected from the group consisting ofdextrin, cyclodextrin, mannit, lactose, hydroxypropylcellulose,methylcellulose, starch, protein, polyvinyl alcohol, polyvinylpyrrolidone, polyacrylic acid, polyethylene oxide, water-solublephotosensitive resin, sulfonated polyisoprene and sulfonatedpolyisoprene copolymer, and/or an inorganic water-soluble particlecomprising of at least one selected from the group consisting ofpotassium acetate, potassium nitrate, potassium carbonate, potassiumbicarbonate, potassium chloride, potassium bromide, potassium phosphateand magnesium nitrate.

13. The composition for a polishing pad according to 12 above, whereinthe amount of said water-soluble particles is 10 to 90% by volume basedon 100% by volume as the total amount of said water-insoluble matrixmaterial and said water-soluble particles.

14. A polishing pad characterized in that at least a part of saidpolishing pad comprises the composition of a water-insoluble matrixmaterial containing a crosslinked polymer and a water-soluble particledispersed in the water-insoluble matrix material.

15. A polishing pad according to 14 above, wherein the elongationremaining after breaking is 100% or less when a test piece comprisingthe water-insoluble matrix material is broken at 80° C.

16. A polishing pad according to 15 above, wherein the Shore D hardnessis 35 or more.

According to the present invention, there can be obtained a compositionfor a polishing pad which can afford a polishing pad in which a pore isformed in the better state, a pore is not choked even by dressing, andthe slurry retaining properties are better. And also, there can beobtained a composition for a polishing pad in which a water-solubleparticle contained in said polishing pad does not absorb moisture and isnot swollen, and which can afford a polishing pad having the highhardness. In addition, according to the invention, there can be obtaineda polishing pad which can perform polishing at the high removal rate.

DETAILED DESCRIPTION OF THE INVENTION

A composition for a polishing pad of the present invention ischaracterized in that it contains a water-insoluble matrix materialcontaining a crosslinked polymer and a water-soluble particle dispersedin the water-insoluble matrix material.

A water-soluble particle is dispersed and contained in the whole ofaforementioned “water-insoluble matrix material” (hereinafter, simplyreferred to as “matrix material”). And, in a polishing pad obtained fromthe present composition for a polishing pad, a pore is formed bydissolving a water-soluble particle present on its most superficiallayer by contacting with water. A pore has the functions of retainingthe slurry and causes the polishing dusts to be transiently retained.The “water-soluble particle” is dissolved or swollen by contacting withthe slurry which is an aqueous dispersion in a polishing pad, and exitsfrom a matrix material. The matrix material may be modified with an acidanhydride group, a carboxyl group, hydroxyl group, an epoxy group, anamino group or the like. This modification can regulate the affinitywith a water-soluble particle and the slurry.

The “crosslinked polymer” constitutes a matrix material and imparts amatrix material with the elastic recovery by the existence of thecross-linking structure. The inclusion of the crosslinked polymer cansuppress to a small level a displacement by shear stress exerted on apolishing pad during polishing, and can effectively suppress excessivestretching of a matrix material during polishing and during dressing andconsequent plastic deformation to choke a pore, and fuzz of the surfaceof polishing pad, and the like. Therefore, a pore is effectively formed,a decrease in the slurry retaining during polishing is small, and fuzzis small, leading to no adverse effect on the polishing flatness

It is preferable that this matrix material has the elongation remainingafter breaking (hereinafter, simply referred to as “breaking remainingelongation”) of 100% or smaller when a test piece comprising a matrixmaterial is broken at 80° C. according to JIS K 6251. That is, it ispreferable that a total distance between marked lines after breaking is2-fold or less of a distance between marked lines before breaking. It ispreferable that this breaking remaining elongation is 30% or smaller,(more preferably 10% or smaller, particularly preferably 5% or smaller,usually 0% or more). When the breaking remaining elongation exceeds100%, fine pieces which have been scraped from the polishing pad surfaceor stretched during polishing and during face updating tend to easilychoke a pore, being not preferable.

The “breaking remaining elongation” is an elongation obtained bysubtracting a distance between marked lines before a test from a totaldistance from a marked line to a broken part of respective test piecesfragmented by breaking when a test piece is broken by a tensile testingmachine at a stretching rate of 500 mm/min. and a test temperature of80° C. using a test piece shape of dumbbell No.3 according to JIS K 6251“Method for Tensile Test of Vulcanized Rubber”. Since the heat isproduced by sliding in the actual polishing, a test was performed at atemperature of 80° C.

Examples of such the crosslinked polymer include curable resins whichare crosslinked by using as a part of a monomer a polyfunctional monomersuch as an urethane resin, an epoxy resin, an acrylic resin, anunsaturated polyester resin, vinyl ester resin, and the like andapplying the external energy such as heat and the like, crosslinkedrubbers obtained by cross-linking-reacting butadiene rubber, 1,2-polybutadiene, isoprene rubber, acrylic rubber,acrylonitrile-butadiene rubber, styrene-butadiene rubber,ethylene-propylene rubber, silicone rubber, fluorine rubber,styrene-isoprene rubber and the like, polymers obtained by cross-linkingpolyethylene, polyvinylidene fluoride, and the like (by a cross-linkingagent, or irradiation with ultraviolet rays or electrons or the like),ionomer and the like. These may be used alone or as a mixture of 2 ormore of them.

Among them, the use of a crosslinked rubber is preferable because thecrosslinked rubber is stable to strong acids or strong alkalis containedin the many slurries and hardly is softened by water absorption. Anamount of the crosslinked rubber contained in a crosslinked polymer maybe selected appropriately, or the entire crosslinked polymer may becomposed of a crosslinked rubber, or the crosslinked polymer may be amixture with other aforementioned crosslinked polymers. Among thesecrosslinked rubbers, rubbers crosslinked using organic peroxides arepreferable. It is preferable to use 1, 2-polybutadiene. 1,2-polybutadiene is preferable because a rubber having the higherhardness is easily obtained as compared with other crosslinked rubbers.

On the other hand, examples of a water-soluble particle dispersed in amatrix material include not only particles which are completelydissolved in water when contacted with it but also particles whichcontain water or the like and, as a result, are swollen into the geland, whereby, are released from a matrix material. Further, examples ofa water-soluble particle include not only particles which are dissolvedin or swollen with water but also particles which are dissolved orswollen when contacted with an aqueous mixed medium containing analcohol solvent such as methanol or the like.

Examples of such the water-soluble particle include organicwater-soluble particles and inorganic water-soluble particles. Examplesof the organic water-soluble particle include particles made of dextrin,cyclodextrin, mannit, saccharides (lactose and the like), celluloses(hydroxypropylcelluloses, methylcelluloses, and the like), starch,protein, polyvinyl alcohol, polyvinyl pyrrolidone, polyacrylic acid,polyethylene oxide, water-soluble photosensitive resin, sulfonatedpolyisoprene, sulfonated polyisoprene copolymer, and the like. Further,examples of the inorganic water-soluble particle include particlesformed of potassium acetate, potassium nitrate, potassium carbonate,potassium bicarbonate, potassium chloride, potassium bromide, potassiumphosphate, magnesium nitrate, and the like. These water-solubleparticles may contain the aforementioned respective materials alone orin combination of 2 or more or them. Moreover, the water-solubleparticle may be one kind of water-soluble particle composed of aprescribed material or 2 or more kinds of water-soluble particlescomposed of different materials.

In addition, it is preferable that this water-soluble particle has aparticle size of 0.1 to 500 μm (more preferably 0.5 to 100 μm) When aparticle size is less than 0.1 μm, since a size of a formed pore issmaller than that of an abrasive used, there is a tendency that apolishing pad which can sufficiently retain the slurry is difficult toobtain. On the other hand, a particle size exceeds 500 mμ, since a sizeof a formed pore is excessive, there is a tendency that the mechanicalstrength and the removal rate of the resulting polishing pad arereduced.

Moreover, it is preferable that the content of this water-solubleparticle is 10 to 90% by volume (more preferably 15 to 60% by volume,more preferably 20 to 40% by volume) when a sum of a matrix material anda water-soluble particle is regarded as 100% by volume. When the contentof a water-soluble particle is less than 10% by volume, a pore is notsufficiently formed in the resulting polishing pad and there is atendency that the removal rate is reduced. On the other hand, when awater-soluble particle is contained at an amount of over 90% by volume,there is a tendency that a water-soluble particle present in theinterior of the resulting polishing pad can not be sufficientlyprevented from swelling or dissolving and it becomes difficult to retainthe hardness and the mechanical strength of a polishing pad at anappropriate value.

In addition, it is preferable that a water-soluble particle is dissolvedin water only when exposed on the superficial layer in a polishing pad,and, in the interior of a polishing pad, a water-soluble particleabsorbs moisture and is not further swollen. For this reason, it ispreferable that a water-soluble particle is provided with an outer shellwhich inhibits moisture absorption in at least a part of the outermostpart. This outer shell may be physically absorbed onto a water-solubleparticle, or chemically bound with a water-soluble particle, or may becontacted with a water-soluble particle by both physical absorption andchemical binding. Examples of a material which forms an outer shellinclude epoxy resin, polyimide, polyamide, polysilicate, and the like.Even when this outer shell is formed on a part of a water-solubleparticle, the aforementioned effects can be sufficiently obtained.

This water-soluble particle has the function of increasing anindentation hardness of a polishing pad (for example, the Shore Dhardness 35 to 100) in a polishing pad in addition to the function offorming a pore. The greater indentation hardness can increase a pressureloaded to the surface of a polishing wafer in a polishing pad. For thisreason, the removal rate can be improved and, at the same time, the highpolishing flatness can be obtained. Therefore, it is particularlypreferable that this water-soluble particle is a solid material whichcan maintain the sufficient indentation hardness in a polishing pad.

In the invention, in order to control the affinity of a matrix materialwith a water-soluble particle as well as the dispersibility of awater-soluble particle in a matrix material, a compatibilizer may beblended therein. Examples of the compatibilizer include block polymersuch as styrene-butadiene-styrene block polymer and the like, randomcopolymer such as styrene-butadiene copolymer, polymer modified with anacid anhydride group, a carboxyl group, a hydroxyl group, an epoxygroup, an oxazoline group, an amino group, and the like, as well asvarious nonionic surface active agent, coupling agent such as silanecoupling agent and the like.

In addition, a matrix material may contain at least one of abrasive,oxidizing agent, polyvalent metal ions, hydroxide and acid of alkalimetal, pH adjusting agent, surfactant, scratch preventing agent, and thelike which have been previously contained in the slurry in addition to awater-soluble particle. This makes it possible to perform polishing bysupplying only water during polishing when a polishing pad formed fromthis composition for a polishing pad is used.

The abrasive may be inorganic particles, organic particles andorganic/inorganic composite particles. As inorganic particles there maybe used particles composed of silicon or metal oxides such as silica,alumina, ceria, titania, zirconia, iron oxide, manganese oxide or thelike.

As organic particles there may be used particles composed ofthermoplastic resins such as (1) polystyrene and styrene-basedcopolymers, (2) (meth)acrylic resins such as polymethyl methacrylate,and acrylic-based copolymers, (3) polyvinyl chloride, polyacetals,saturated polyesters, polyamides, polyimides, polycarbonates and phenoxyresins, and (4) polyolefins such as polyethylene, polypropylene,poly-1-butene, poly-4-methyl-1-pentene, and olefin-based copolymers.

Also, the organic particles, a polymer with a crosslinked structureobtained by copolymerization of styrene, methyl methacrylate or the likewith divinylbenzene, ethyleneglycol dimethacrylate or the like may alsobe used. The degree of crosslinking can be used to adjust the hardnessof the organic particles.

There may also be used organic particles composed of thermosettingresins such as phenol resins, urethane resins, urea resins, melamineresins, epoxy resins, alkyd resins and unsaturated polyester resins.

These inorganic particles and organic particles may be used alone or incombinations of two or more.

Organic/inorganic composite particles is not particularly limited, theorganic/inorganic composite particles may have the organic particles andinorganic particles formed integrally to an extent so as not to easilyseparate during the polishing process, and there are no particularrestrictions on their types or structures.

As composite particles there may be used particles formed bypolycondensation of an alkoxysilane, aluminum alkoxide, titaniumalkoxide or the like in the presence of polymer particles ofpolystyrene, polymethyl methacrylate or the like, and bonding ofpolysiloxane or the like on at least the surface of the polymerparticles. The resulting polycondensate may be directly bonded to thefunctional group of the polymer particles, or it may be bonded via asilane coupling agent or the like.

The polycondensate does not necessarily need to be chemically bonded tothe polymer particles, and the three-dimensionally formed polycondensatemay by physically held on the surface of the polymer particles. Silicaparticles or alumina particles may also be used instead of analkoxysilane. These may also be held by intertwining with thepolysiloxane, or they may be chemically bonded to the polymer particlesby their functional groups, such as hydroxyl groups.

As examples of specific oxidizing agents there may be mentioned hydrogenperoxide, organic peroxides such as peracetic acid, perbenzoic acid,tert-butylhydroperoxide, and the like, permanganate compounds such aspotassium permanganate, and the like, bichromate compounds such aspotassium bichromate, and the like, halogenate compounds such aspotassium iodate, and the like, nitric compounds such as nitric acid,iron nitrate, and the like, perhalogenate compounds such as perchloricacid, and the like, transition metal salts such as potassiumferricyanide, and the like, persulfuric compounds such as ammoniumpersulfate, and the like, and heteropoly acids. Particularly preferredamong these oxidizing agents are hydrogen peroxide and organic peroxideswhich contain no metals and whose decomposition products are harmless.Including such oxidizing agents can give an even more vastly improvedremoval rate.

The content of the oxidizing agent may be preferably 0.01 to 20 parts,more preferably 0.05 to 20 parts and particularly 0.1 to 5 parts, in 100parts of the non-water-soluable matrix material. Since sufficientimprovement in the removal rate can be achieved if the oxidizing agentis added at 0.01 parts, there is no need to add it at greater than 20parts.

As polyvalent metal ions there may be mentioned metal ions such asaluminum, titanium, vanadium, chromium, manganese, iron, cobalt, nickel,copper, zinc, germanium, zirconium, molybdenum, tin, antimony, tantalum,tungsten, lead and cerium. Any one of these may be used, or two or morepolyvalent metal ions may be used in combination.

The polyvalent metal ion content may be up to 3000 ppm, and preferablyfrom 3 to 3000 ppm, in the aqueous dispersion.

The polyvalent metal ion may be produced by mixing with the aqueousmedium a salt such as a nitric acid salt, sulfuric acid salt or aceticacid salt or a chelate containing a polyvalent metal element, and it mayalso be produced by mixing an oxide of a polyvalent metal element. Theremay also be used a compound that produces a monovalent metal ion whenmixed with the aqueous medium, but whose ion becomes a polyvalent metalion by the oxidizing agent. Of these various salts and chelates, ironnitrate is preferred because of its particularly excellent effect ofimproving the removal rate.

As alkali metal hydroxides there may be used sodium hydroxide, potassiumhydroxide, rubidium hydroxide, cesium hydroxide and the like. And anacid is not particularly restricted, and any organic acid or inorganicacid may be used. As organic acids there may be mentionedpara-toluenesulfonic acid, dodecylbenzenesulfonic acid, isoprenesulfonicacid, gluconic acid, lactic acid, citric acid, tartaric acid, malicacid, glycolic acid, malonic acid, formic acid, oxalic acid, succinicacid, fumaric acid, maleic acid and phthalic acid. These organic acidsmay be used alone or in combinations of two or more. As inorganic acidsthere may be mentioned nitric acid, hydrochloric acid and sulfuric acid,and any one or more of these may be used. An organic acid and aninorganic acid may also be used in combination.

The contents of these acids may 0.05 to 20 parts, especially 0.1 to 15parts and more preferably 0.3 to 10 parts in 100 parts of thewater-insolublematrix material.

The pH adjustment may be accomplished with an acid such as nitric acidor sulfuric acid, or with an alkali such as pottasium hydroxide, sodiumhydroxide or ammonia. Adjustment of the pH of the aqueous dispersion canincrease the removal rate, and the pH is preferably determined asappropriate within the range where the abrasive can exist stably inconsideration of the electrochemical properties of the working surface,the dispersability and stability of the polymer particles and theremoval rate.

As surfactants there may be used cationic surfactants, anionicsurfactants or non-ionic surfactants. As cationic surfactants there maybe mentioned fatty amines, aliphatic ammonium salts and the like. Asanionic surfactants there may be mentioned carboxylic acid salts such asfatty acid soaps and alkylether carboxylic acid salts, sulfonic acidsalts such as alkylbenzenesulfonic acid salts, alkylnaphthalenesulfonicacid salts and α-olefinsulfonic acid salts, sulfuric acid ester saltssuch as higher alcohol sulfuric acid ester salts and alkylether sulfuricacid salts, and phosphoric acid esters such as alkylphosphoric acidesters and the like.

Particularly preferred as surfactants are non-ionic surfactants becauseof their notable effect of reducing scratches. As non-ionic surfactantsthere may be mentioned ethers such as polyoxyethylene alkyl ether, etheresters such as polyoxyethylene ethers of glycerin esters, and esterssuch as polyethylene glycol fatty acid esters, glycerin esters, sorbitanesters and the like.

The content of the surfactant in the scratch inhibitor comprising asurfactant may be 0.01 to 10 wt %, preferably 0.03 to 5 wt % and morepreferably 0.05 to 3 wt %, especially for a non-ionic surfactant. If thesurfactant content is less than 0.01 wt %, the generation of scratchesmay not be sufficiently reduced, and if it exceeds 10 wt % there may bea tendency toward lower heat resistance and coloring resistance of theorganic particles.

As scratch inhibitors there may be used at least one from among (1)biphenol, (2) bipyridyl, (3) 2-vinylpyridine and 4-vinylpyridine, (4)salicylaldoxime, (5) o-phenylenediamine and m-phenylenediamine, (6)catechol, (7) o-aminophenol, (8) thiourea, (9) an N-alkylgroup-containing (meth)acrylamide, (10) an N-aminoalkyl group-containing(meth)acrylamide, (11) a heterocyclic compound with a heteropentacycleand with no aromatic ring forming the skeleton, (12) a heterocycliccompound with a heteropentacycle and with an aromatic ring forming theskeleton, (13) phthalazine, (14) a compound with a heterohexacyclebearing three nitrogen atoms, (15) a surfactant, and a derivative of anyof compounds (1) through (14). As derivatives there may be mentionedthese compounds to which are bonded short-chain alkyl groups of 1 to 3carbons, amino groups, hydroxyl groups, mercapto groups and the like.

These scratch inhibitors may also comprise any desired combinations oftwo or more from among the compounds of (1) through (14) and theirderivatives, and the surfactant of (15).

As heterocyclic compounds with a heteropentacycle and with an aromaticring forming the skeleton, there may be mentioned7-hydroxy-5-methyl-1,3,4-triazaindolizine, 3H-1,2,3-triazolo[4,5-b]pyridin-3-ol, 1H-tetrazole-1-acetic acid,1-(2-dimethylaminoethyl)-5-mercaptotetrazole, bismuthiol, 4,5-dicyanoimidazole, adenine, 1-phenyl-5-mercapto-1H-tetrazole,3-mercapto-1,2,4-triazole, 2-amino-4,5-dicyano-1H-imidazole,4-amino-1,2,4-triazole, 5-amino-1H-tetrazole, 2-mercaptothiazoline,guanine, 1-phenyl-5-mercapto-1H-tetrazole,4-amino-3-hydrazino-5-mercapto-1,2,4-triazole,3-mercapto-4-methyl-4H-1,2,4-triazole, 1H-tetrazole and the like.

As heterocyclic compounds with a heteropentacycle and with an aromaticring forming the skeleton, there may be mentioned benzotriazoles such as5-methyl-1H-benzotriazole, tolyltriazole, benzimidazole, benzofloxane,2,1,3-benzothiadiazole, 2-mercaptobenzothiazole,2-mercaptobenzothiadiazole, 2-mercaptobenzooxazole,2-aminobenzothiazole, 2-mercaptobenzothiazole,2-amino-6-methylbenzothiazole and the like.

As compounds with a heterohexacycle bearing three nitrogen atoms theremay be mentioned, melamine, 3-amino-5, 6-dimethyl-1,2,4-triazine,2,4-diamino-6-diallylamino-1,3,5-triazine, benzoguanamine andthiocyanuric acid.

Among these are preferred 7-hydroxy-5-methyl-1,3, 4-triazaindolizine,3-mercapto-1,2,4-triazole, 1-phenyl-5-mercapto-1H-tetrazole and5-methyl-1H-benzotriazole because of their superior effect of reducingscratches, and 7-hydroxy-5-methyl-1, 3,4-triazaindolizine isparticularly preferred because of its notable effect of reducingscratches.

The content of the scratch inhibitor comprising these compounds (1)through (14) or their derivatives is preferably 0.001 to 5 wt %referably 0.005 to 2 wt % and even more preferably 0.01 to 1 wt %. Ifthe content is less than 0.001 wt % the generation of scratches may notbe sufficiently reduced, and if it exceeds 5 wt % the scratch inhibitormay not dissolve sufficiently and may tend to precipitate.

Further, various additives such as a filler, a softening agent, anantioxidant, an ultraviolet absorbing agent, an antistatic agent, alubricant, a plasticizer, and the like may be added to the compositionsfor a polishing pad of the present invention, if necessary. Further, thecomposition may be reacted and crosslinked by adding a reactive additivesuch as sulfur, peroxide, and the like. In particular, as a filler,materials which improve the stiffness such as calcium carbonate,magnesium carbonate, talc, clay, and the like, and materials and thelike having the polishing effects such as silica, alumina, ceria,zirconia, titanium oxide, ziriconium oxide, manganese dioxide, manganesetrioxide, barium carbonate, and the like may be used.

A process for preparing this composition for a polishing pad is notparticularly limited. When the process has a kneading step, kneading canbe performed by the known kneading machine or the like. Examples of thekneading machine include a roll, a kneader, a Banbury mixer, an extruder(single screw, multiple screws), and the like. The kneaded compositionfor a polishing pad may be processed into the desired shape such assheet, block, film, and the like by performing press molding, extrusionmolding, injection molding, and the like. In addition, this can beprocessed into the desired size to obtain a polishing pad.

In addition, a method for dispersing water-soluble particle in a matrixmaterial is not particularly limited but a matrix material, awater-soluble particle and other additives, and the like may be usuallykneaded for dispersion. In this kneading, a matrix material is kneadedby heating for easy processing and it is preferable that a water-solubleparticle is a solid at a temperature of this time point. When awater-soluble particle is a solid, it becomes easy to disperse awater-soluble particle so that the aforementioned preferable particlesize is manifested, regardless of a magnitude of compatibility with amatrix material. Therefore, it is preferable that a kind of awater-soluble particle is selected depending upon a temperature forprocessing a matrix material used.

A polishing pad of the present invention is characterized in that atleast a part of it is composed of the composition for a polishing pad.

It is preferable that the Shore D hardness of the polishing pad of thepresent invention is 35 or more (usually 100 or smaller, more preferably50 to 90, more preferably 60 to 85). When this Shore D hardness is lessthan 35, there is a tendency that a pressure which can be applied to amaterial to be polished during polishing is decreased, and the removalrate is reduced and the polishing flatness becomes insufficient.

In addition, it is preferable that a size of a pore is 0.1 to 500 μm(more preferably 0.5 to 100 μm). When this pore size is less than 0.1μm, since a size is smaller than a size of an abrasive, there is atendency that it becomes difficult to retain an abrasive sufficiently.On the other hand, when a size of a pore exceeds 500 μm, there is atendency that it becomes difficult to obtain the sufficient strength andindentation hardness.

In order to improve the dischargeabitliy of the slurry or the like, agroove or a dot pattern may be formed on the surface (polishing side) ofthe present polishing pad in the prescribed shape. Alternatively, it ispossible to obtain a polishing pad exhibiting a multilayer structuresuch as a polishing pad in which, for example, a softener layer isapplied to the back (opposite to the polishing side) of this polishingpad. Moreover, the shape of this polishing pad is not particularlylimited but can be appropriately selected from the disc, the belt, theroller shapes, and the like depending upon a polishing apparatus.

Description of the Preferred Embodiments

The present invention will be specifically explained by way of Examples.

Preparation of a composition for a polishing pad and molding of apolishing pad

EXAMPLE 1

100 parts by weight of 1, 2-polybutadiene (manufactured by JSR Co.,Ltd., trade name “JSR RB830”) which will be a matrix material bycross-linking later and 100 parts by weight of β-cyclodextrin(manufactured by Yokohamakokusai Biokenkyujo K K., trade name “Dexypearlβ-100”) as a water-soluble particle were kneaded with a kneader heatedat 120° C. Thereafter, 0.3 part by weight of an organic peroxide(manufactured by Nihonyushi Co., Ltd., trade name “Perhexin 25B”) wasadded, further kneaded, and reacted to crosslinking and molded at 190°C. for 10 minutes in a mold to obtain a polishing pad having a diameterof 60 cm and a thickness of 2 mm. A volumetric fraction of awater-soluble particle relative to the whole polishing pad (a volumetricfraction of a water-soluble particle relative to a sum of a matrixmaterial and a water-soluble particle like volumetric fraction of awater-soluble particle relative to a sum of acrosslinked polymer and awatersoluble particle) was about 40%.

EXAMPLE 2

100 parts by weight of 1, 2-polybutadiene (manufactured by “JSR Co.,Ltd., JSR RB840”) which will be a matrix material by crosslinking laterand 230 parts by weight of β-cyclodextrin coated with a polypeptide(manufactured by Yokohamakokusai baiokenkyujo Co., Ltd., tradename“Dexypearl β-100”) as a water-soluble particle were kneaded with akneader heated at 120° C. Thereafter, 0.3 part by weight of an organicperoxide (manufactured by Nihonyushi Co., Ltd., trade name “Perhexin25B”) was added, further kneaded, and reacted to crosslink and molded at190° C. for 10 minutes in a mold to obtain a polishing pad having adiameter of 60 cm and a thickness of 2 mm. A volumetric fraction of awater-soluble particle relative to the whole polishing pad (a volumetricfraction of a water-soluble particle relative to a sum of a matrixmaterial and a water-soluble particle like volumetric fraction of awater-soluble particle relative to a sum of a crosslinked polymer and awater-soluble particle) was about 60%.

Comparative Example 1

100 parts by weight of an ethylene-vinyl alcohol copolymer resin whichis a non-crosslinked thermoplastic resin (manufactured by Kurare Co.,Ltd., trade name “Evar EP-F101”) and 100 parts by weight ofβ-cyclodextrin (manufactured by Yokohamakokusai biokenkyujo Co., Ltd.,trade name “Dexypearl β-100”) as a water-soluble particle were kneadedwith a kneader heated at 200° C., and heat-pressed to mold at 200° C. toobtain a polishing pad having a diameter of 60 cm and a thickness of 2mm. A volumetric fraction of a water-soluble particle relative to thewhole polishing pad (a volumetric fraction of a water-soluble particlerelative to a sum of a matrix material and a water-soluble particle likevolumetric fraction of a water-soluble particle relative to a sum of acrosslinked polymer and a water-soluble particle) was about 44%.

Comparative Example 2

1, 2-polybutadiene and β-cyclodexitrine as in Example 1 were kneaded,and press-molded at 120° C. without cross-linking reaction to obtain apolishing pad having a diameter of 60 cm and a thickness of 2 mm. Avolumetric fraction of a water-soluble particle relative to the wholepolishing pad (a volumetric fraction of a water-soluble particlerelative to a sum of a matrix material and a water-soluble particle likevolumetric fraction of a water-soluble particle relative to a sum of acrosslinked polymer and a water-soluble particle) was about 40%.

Polishing Assessment of Polishing Performance

Respective polishing pads obtained in Examples 1 and 2 and ComparativeExamples 1 and 2 were mounted on a surface plate of a polishing machine(manufactured by SFT Corp., model “Lapmaster LM-15”), and a silicamembrane wafer was polished under the conditions of the flat surfacerotation number of 50 rpm and the slurry flow rate of 100 cc/min. toassess the difference in the polishing performance of each polishing padand the result thereof are shown Table 1. The removal rate was obtainedby measuring a change in a membrane thickness with an optical membranethickness measuring machine.

Further, the surface of a polishing pad was subjected to dressing(grinding with #400 diamond whetstone for 5 minutes) and, thereafter,the state of a pore on this surface was observed with an electronmicroscope. This result is also shown in Table 1. “O” in Table 1indicates that a better pore can be confirmed and “X” indicates that apart of a pore is choked.

TABLE 1 Example Comparative example 1 2 1 2 Removal rate (μm/min.) 190250 60 10 State of a pore ∘ ∘ x x Breaking elongation (%) 100100 >600 >600 Breaking remaining elongation (%) 0 0 510 220

In order to measure the breaking remaining elongation of matrixmaterials used in Examples 1 and 2 and Comparative Examples 1 and 2,materials from which a water-soluble particle is omitted from respectiveExamples 1 and 2 and Comparative Examples 1 and 2 were kneaded andmolded similarly to make sheets. The sheets were cut into the dumbbellNo.3 test piece shape shown in JIS K 6251 to obtain test pieces.

These respective test pieces were stretched to break at a distancebetween marked lines of 20 mm, a stretching rate of 500 mm/min. and atest temperature of 80° C. according to JIS K 6251, and the breakingremaining elongation was calculated based on the aforementionedstandard. In a test piece which did not break even when stretched to amaximum 600%, the piece was forced to cut at this elongation of 600%,and the breaking remaining elongation was calculated. These breakingremaining elongation are also shown in Table 1.

From the results of Table 1, in Examples 1 and 2 in which a matrixmaterial is a crosslinked polymer, a pore is formed in the better stateeven after dressing. The breaking remaining elongation of matrixmaterials used in these polishing pads were all 0%, and it can be seenthat no elongation after breaking is perceived. It can be seen that theremoval rate is as high as 190 to 250 nm/mm. in such the polishing pad.

To the contrary, in Comparative Example 1, a non-crosslinkedthermoplastic resin was used as a matrix material. It can be seen thatthis non-crosslinked thermoplastic resin has the very large breakingremaining elongation of 510% and, therefore, ductility. In addition, apart of pore was choked by dressing. Therefore, the removal rate is 60nm/mm. being 32% of that in Example 1 and 24% of that in Example 2. Onthe other hand, in Comparative Example 2, since a matrix material usedin Examples 1 and 2 is used as a non-crosslinked material, the samplehas not the elastic recovery. For this reason, the breaking remainingelongation is as large as 220%. In addition, a part of pore was chokedby dressing. Therefore, the removal rate is 10 nm/min., being 5% of thatof Example 1 and 4% of that of Example 2.

What is claimed is:
 1. A composition for a polishing pad which comprisesa water-insoluble matrix material containing a crosslinked polymer andwater-soluble particles dispersed in the water-insoluble matrixmaterial, wherein said water-soluble particles are provided with anouter shell for inhibiting moisture absorption in at least a part of theoutermost part, wherein said water-soluble particles are selected fromthe group consisting of (1) organic water-soluble particles comprisingat least one material selected from the group consisting of dextrin,cyclodextrin, mannit, lactose, hydroxypropylcellulose, methylcellulose,starch, protein, polyvinyl alcohol, polyvinyl pyrrolidone, polyacrylicacid, polyethylene oxide, water-soluble photosensitive resin, sulfonatedpolyisoprene and sulfonated polyisoprene copolymer, (2) inorganicwater-soluble particles comprising at least one material selected fromthe group consisting of potassium acetate, potassium nitrate, potassiumcarbonate, potassium bicarbonate, potassium chloride, potassium bromide,potassium phosphate and magnesium nitrate, and (3) mixtures of (1) and(2).
 2. The composition for a polishing pad according to claim 1,wherein the amount of said water-soluble particles is 10 to 90% byvolume based on 100% by volume as the total amount of saidwater-insoluble matrix material and said water-soluble particles.
 3. Acomposition for a polishing pad which comprises a water-insoluble matrixmaterial containing a crosslinked polymer and organic water-solubleparticles comprising at least one material selected from the groupconsisting of dextrin, cyclodextrin, mannit, lactose,hydroxpropylcellulose, methylcellulose, starch, protein, polyvinylalcohol, polyvinyl pyrrolidone, polyacrylic acid, polyethylene oxide,water-soluble photosensitive resin, sulfonated polyisoprene andsulfonated polyisoprene copolymer, dispersed in the water-insolublematrix material, wherein the elongation remaining after breaking is 100%or less when a test piece comprising the water-insoluble matrix materialis broken at 80° C.
 4. A composition for a polishing pad which comprisesa water-insoluble matrix material containing a crosslinked polymer andorganic water-soluble particles comprising at least one materialselected from the group consisting of dextrin, cyclodextrin, mannit,lactose, hydroxypropylcellulose, methylcellulose, starch, protein,polyvinyl alcohol, polyvinyl pyrrolidone, polyacrylic acid, polyethyleneoxide, water-soluble photosensitive resin, sulfonated polyisoprene andsulfonated polyisoprene copolymer, dispersed in the water-insolublematrix material, wherein said water-insoluble matrix material ismodified with at least one group selected from the group consisting ofan acid anhydride group, a carboxyl group, a hydroxyl group, an epoxygroup and an amino group.
 5. A composition for a polishing pad whichcomprises a water-insoluble matrix material containing a crosslinkedpolymer and organic water-soluble particles comprising at least onematerial selected from the group consisting of dextrin, cyclodextrin,mannit, lactose, hydroxypropylcellulose, methylcellulose, starch,protein, polyvinyl alcohol, polyvinyl pyrrolidone, polyacrylic acid,polyethylene oxide, water-soluble photosensitive resin, sulfonatedpolyisoprene and sulfonated polyisoprene copolymer, dispersed in thewater-insoluble matrix material, wherein said crosslinked polymer is (I)a crosslinked polymer of rubber selected from the group consisting of1,2-polybutadiene, butadiene rubber, isoprene rubber, acrylic rubber,acrylonitrile-butadiene rubber, styrene-butadiene rubber,ethylene-propylene rubber, silicone rubber, fluorine rubber andstyrene-isoprene rubber, (2) a crosslinked polymer of resin selectedfrom the group consisting of polyethylene and polyvinylidene fluoride,or (3) an ionomer.
 6. A composition for a polishing pad which comprisesa water-insoluble matrix material containing a crosslinked polymer andorganic water-soluble particles comprising at least one materialselected from the group consisting of dextrin, cyclodextrin, mannit,lactose, hydroxypropylcellulose, methylcellulose, starch, protein,polyvinyl alcohol, polyvinyl pyrrolidone, polyacrylic acid, polyethyleneoxide, water-soluble photosensitive resin, sulfonated polyisoprene andsulfonated polyisoprene copolymer, dispersed in the water-matrixmaterial, wherein the amount of said water-soluble particles is 10 to90% by volume based on 100% by volume as the total amount of saidwater-insoluble matrix material and said water-soluble particles.
 7. Acomposition for a polishing pad which comprises a water-insoluble matrixmaterial containing a crosslinked polymer and organic water-solubleparticles comprising at least one material selected from the groupconsisting of dextrin, cyclodextrin, mannit, lactose,hydroxypropylcellulose, methylcellulose, starch, protein, polyvinylalcohol, polyvinyl pyrrolidone, polyacrylic acid, polyethylene oxide,water-soluble photosensitive resin, sulfonated polyisoprene andsulfonated polyisoprene copolymer, dispersed in the water-insolublematrix material, wherein said water-soluble particles are provided withan outer shell for inhibiting moisture absorption in an at least a partof the outermost part.
 8. The composition for a polishing pad accordingto claim 7, wherein said outer shell is comprised of at least onematerial selected from the group consisting of polypeptide, epoxy resin,polyimide, polyamide and polysilicate.
 9. A composition for a polishingpad which comprises a water-insoluble matrix material containing apolymer crosslinked by an organic peroxide and organic water-solubleparticles comprising at least one material selected from the groupconsisting of dextrin, cyclodextrin, mannit, lactose,hydroxypropylcellulose, methylcellulose, starch, protein, polyvinylalcohol, polyvinyl pyrrolidone, polyacrylic acid, polyethylene oxide,water-soluble photosensitive resin, sulfonated polyisoprene andsulfonated polyisoprene copolymer dispersed in the water-insolublematrix material, wherein said crosslinked polymer is (1) a crosslinkedpolymer of rubber selected from the group consisting of1,2-polybutadiene, butadiene rubber, isoprene rubber, acrylic rubber,acrylonitrile-butadiene rubber, styrene-butadiene rubber,ethylene-propylene rubber, silicone rubber, fluorine rubber andstyrene-isoprene rubber, (2) a crosslinked polymer of resin selectedfrom the group consisting of polyethylene and polyvinylidene fluoride,or (3) an ionomer.
 10. A composition for a polishing pad which comprisesa water-insoluble matrix material containing a polymer crosslinked by anorganic peroxide and organic water-soluble particles comprising at leastone material selected from the group consisting of dextrin,cyclodextrin, mannit, lactose, hydroxypropylcellulose, methylcellulose,starch, protein, polyvinyl alcohol, polyvinyl pyrrolidone, polyacrylicacid, polyethylene oxide, water-soluble photosensitive resin, sulfonatedpolyisoprene and sulfonated polyisoprene copolymer dispersed in thewater-insoluble matrix material, wherein said water-insoluble matrixmaterial is modified with at least one group selected from the groupconsisting of an acid anhydride group, a carboxyl group, a hydroxylgroup, an epoxy group and an amino group.
 11. A composition for apolishing pad which comprises a water-insoluble matrix materialcontaining a polymer crosslinked by an organic peroxide and organicwater-soluble particles comprising at least one material selected fromthe group consisting of dextrin. cyclodextrin, mannit, lactose,hydroxypropylcellulose, methylcellulose, starch, protein, polyvinylalcohol, polyvinyl pyrrolidone, polyacrylic acid, polyethylene oxide,water-soluble photosensitive resin, sulfonated polyisoprene andsulfonated polyisoprene copolymer dispersed in the water-insolublematrix material wherein the amount of said water-soluble particles is 10to 90% by volume based on 100% by volume as the total amount of saidwater-insoluble matrix material and said water-soluble particles.
 12. Acomposition for a polishing pad which comprises a water-insoluble matrixmaterial containing a polymer crosslinked by an organic peroxide andorganic water-soluble particles comprising at least one materialselected from the group consisting of dextrin, cyclodextrin, mannit,lactose, hydroxypropylcellulose, methylcellulose, starch, protein,polyvinyl alcohol, polyvinyl pyrrolidone, polyacrylic acid, polyethyleneoxide, water-soluble photosensitive resin, sulfonated polyisoprene andsulfonated polyisoprene copolymer dispersed in the water-insolublematrix material wherein said water-soluble particles are provided withan outer shell for inhibiting moisture absorption in an at least a partof the outermost part.
 13. The composition for a polishing pad accordingto claim 12, wherein said outer shell is comprised of at least onematerial selected from the group consisting of polypeptide, epoxy resin,polyimide, polyamide and polysilicate.
 14. A composition for a polishingpad which comprises a water-insoluble matrix material containing acrosslinked polymer and water-soluble particles dispersed in thewater-insoluble matrix material, wherein said water-soluble particlesare provided with an outer shell for inhibiting moisture absorption inat least a part of the outermost part, wherein said crosslinked polymeris (1) a crosslinked polymer of rubber selected from the groupconsisting of 1,2-polybutadiene, butadiene rubber, isoprene rubber,acrylic rubber, acrylonitrile-butadiene rubber, styrene-butadienerubber, ethylene-propylene rubber, silicone rubber, fluorine rubber andstyrene-isoprene rubber, (2) a crosslinked polymer of resin selectedfrom the group consisting of polyethylene and polyvinylidene fluoride,or (3) an ionomer.
 15. A composition for a polishing pad which comprisesa water-insoluble matrix material containing a crosslinked polymer andwater-soluble particles dispersed in the water-insoluble matrixmaterial, wherein said water-soluble particles are provided with anouter shell for inhibiting moisture absorption in at least a part of theoutermost part, wherein said water-insoluble matrix material is modifiedwith at least one group selected from the group consisting of an acidanhydride group, a carboxyl group, a hydroxyl group, an epoxy group andan amino group.
 16. A composition for a polishing pad which comprises awater-insoluble matrix material containing a crosslinked polymer andwater-soluble particles dispersed in the water-insoluble matrixmaterial, wherein said water-soluble particles are provided with anouter shell for inhibiting moisture absorption in at least a part of theoutermost part, wherein said outer shell is comprises of at least onematerial selected from the group consisting of polypeptide, epoxy resin,polyimide, polyamide and polysilicate.
 17. A composition for a polishingpad which comprises a water-insoluble matrix material containing acrosslinked polymer and water-soluble particles dispersed in thewater-insoluble matrix material, wherein said water-soluble particlesare provided with an outer shell for inhibiting moisture absorption inat least a part of the outermost part, wherein said water-solubleparticles have a particle size of 0.1 to 500 μm.
 18. A composition for apolishing pad which comprises a water-insoluble matrix materialcontaining a crosslinked polymer and organic water-soluble particlescomprising at least one material selected from the group consisting ofdextrin, cyclodextrin, mannit, lactose, hydroxypropylcellulose,methylcellulose, starch, protein, polyvinyl alcohol, polyvinylpyrrolidone, polyacrylic acid, polyethylene oxide, water-solublephotosensitive resin, sulfonated polyisoprene and sulfonatedpolyisoprene copolymer, dispersed in the water-insoluble matrix materialwherein said water-soluble particles have a particle size of 0.1 to 500μm.